Help with wiring of Room Thermostat - Honeywell T6160

10 May 2011
Reaction score
United Kingdom
I've got a T6160 which I want to replace with a Horstmann DRT2 and need help with the wiring.
The T6160 has terminals numbered and wired as follows
T5 - No wire
T2 - Blue
T3 - Red
T4 - No Wire
T1 - Yellow.

Testing the wires, with a sparks screwdiver (with the neon in the handle) I see the following:

T5 - always 'dead'
T2 - always 'dead'
T3 - always live
T4 - 'dead' when system is calling for heat but live when heat satisfied
T1 - Always live (but strangely the neon is brighter when the system is calling for heat).

I'm not clear on which is the real live (T1 or T3) but I guess that should be connected to COM on the DRT2.

The DRT2 also has NO and NC connections so next question is; which of these do I use and what wire do I connect to it?

The boiler is a Worcester Bosch condensing job, about 7 years old

Any help much appreciated

Sponsored Links

Terminal 1 = Live from programmer(yellow)

Terminal 2 = Neutral (blue)

Termainal 3 = Switch live (red)

NO = Normally open

NC = Normally closed

Connect the red wire to NO

Connect the yellow to Com

Insulate the blue wire and leave it loose inside the room stat, do not cut it off as it may be of use at a later date!

Have fun!!!
thanks for that quick reply.

Just tried it and both CH and water heating are activated constantly. Def not the room temp causing the bolier to fire, set down to 15degrees.

any thoughts? Thanks in advance

Hi Gerry.

Was you changing the room stat because of the problem with the heating and hot water permanently on, or is this a new problem?

I don't want to teach you to suck eggs (very old saying) but it all starts from the programmer, when heating or hot water is selected a live is put out to the room stat or cylinder stat, if the stat is calling for heat then the live is then passed onto the valve or valves ( 2 x 2 port or a 3 port), the valve operates and sends a live via the orange cable to the boiler.

I need to know the programmer you have and the system type as in "S" plan (2 valves) or a "Y" plan (mid position valve)

Could be a wiring fault, has anyone had their fingers in the wiring centre?or a faulty motorised valve.

Hope this helps

Sponsored Links
Hi Brian,
there were (are) no probs with the system at all, only reason for changing the stat is I figure that at probably 35 years old it's probably a bit less than 100% accurate in operation.

So i have put the old stat back into place and everything works as expected.

The boiler is Worcester bosch as I said in initial post (26cdi Xtra) and the programmer is also WB and installed in the boiler housing. The user guide describes it as a 'single channel programmer' but there is no model id

because the boiler provides instant hot water then the only time it should call for heat is when the cold water tap is running. That's all been fine.

Should also say the installation (bolier that is ) has been in for 7 years.

hopefully that gives you a bit more to work on.

I didnt appreciate you was talking about a combi, your best bet is to look at the connections in the boiler, you should have a "NS" "LS" "LR"

"LS" goes to "com" on the Horstmann

"LR" goes to "NO" on the Horstmann

"NS" = Neurtral, this is not required on the Horstmann

Try that !

PS If the heating stays on, swap the wire you put on "NO" to "NC"

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local